An expander works opposite to a compressor and operates when the signal falls below the set threshold. It increases the dynamic range of a signal.

Figure 1 - Graph showing how the signal drops quickly below a set threshold

Expanders can be used in place of noise gates, as the drop off of the signal level below the threshold produces a more subtle and transparent effect rather than a sharp cut off of a noise gate.

An expansion ratio is the inverse of a compression ratio for example, instead of 4:1 as seen with a compressor; an expander will have a ratio of 1:4.

Back to top of page